Bremen 2017 – scientific programme

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P: Fachverband Plasmaphysik

P 4: Plasma Technology

P 4.1: Invited Talk

Monday, March 13, 2017, 14:00–14:30, HS 2010

Atmospheric reactive plasma jet machining technologies for ultra-precision optical surface manufacturing — •Thomas Arnold — Leibniz-Institut für Obrflächenmodifizierung e.V. Leipzig/TU Dresden

Atmospheric chemically reactive plasma jets are versatile tools utilized for ultra-precision surface machining. Nowadays, optical elements like lenses and mirrors require very high surface form accuracy and low waviness and micro-roughness in the range of a few nanometers or even below. At the same time, optical surface shapes differ significantly from simple basic forms like planar, spherical or cylindrical geometries. In modern optical applications e.g. for laser beam shaping, space-based astronomical telescopes, or synchrotron beam-lines optics, more and more complex aspherical or freeform surface are required. Deterministic and precise machining of optical materials like fused silica, silicon or silicon carbide by reactive plasma jets has shown a great potential over conventional mechanical-abrasive optical manufacturing since no mechanical forces are exerted to the surface and the chemical nature of plasma surface-interaction is utilized to well controlled local damage-free surface modification. Plasma jets containing halogenated precursors (e.g. CCl4, CF4) are applied in dry etching processes to remove surface material, while polymer forming precursors (e.g. CH4, hexamethyldisiloxane HMDSO) are employed for localized thin film deposition. The presentation will cover problems of plasma-surface interactions as well as technology related aspects in plasma assisted surface machining processes.